Simple Self-Diagnosis by Malfunction Code For Daikin Indoor Unit
For error codes beginning with A or C, stay on this page and scroll down
For error codes beginning with 6, 7, 8 or 9, find causes here
For error codes beginning with U, find causes here
For error codes beginning with E, F, H, J, L, M or P, find causes here
| Indoor Unit Error Codes and Contents | Supposed causes | Parts affected |
|---|---|---|
| A0 External protection device activated | External protection device connected to the terminal strip T1-T2 of indoor unit is activated | SkyAir, VRV, Package |
| A1 Malfunction of indoor unit PCB | Defective indoor unit PCB External factor (noise etc) | RA, SkyAir, VRV, Heat reclaim ventilator, Chiller |
| A3 Drain Level Control System Abnormality | Drain clogging, upward slope, etc Defective drain pump Defective float switch or short circuit connector | RA, SkyAir, VRV, Heat reclaim ventilator, Fan coil |
| A4 Malfunction of freezing protection | Shortage of water volume Low water temperature setting Defective water temperature thermistor | RA, SkyAir, VRV, Package, Chiller, Fan coil |
| A5 High pressure control in heating, freeze-up protection control in cooling | Clogged air filter of indoor unit and short circuit Defect of indoor unit heat exchanger thermistor | RA, SkyAir, VRV, Package |
| A6 Malfunction of fan motor | Broken wires in, short circuit of, or disconnection of connectors from the fan motor harness Defective fan motor Defective indoor unit PCB | RA, SkyAir, VRV, Package, Heat reclaim ventilator |
| A7 Malfunction of swing flap motor | Defective swing flap motor Defective indoor unit PCB Defective connection cable Defective airflow direction adjusting flap-cam | SkyAir, VRV |
| A8 Malfunction of power supply or AC input overcurrent | Defective power supply voltage Defective connection on signal line Defective wiring | SkyAir, VRV, Heat reclaim ventilator |
| A9 Malfunction of electronic expansion valve | Defective electronic expansion valve coil Defective indoor unit PCB Defective relay cables | SkyAir, VRV, Package, Heat reclaim ventilator. Chiller |
| AA Heater overheat | 26WH is activated | Package, Chiller |
| AF Malfunction of humidifier system | Humidifier unit (optional accessory) leaking Defective drain piping (upward slope, etc.) Defective indoor unit PCB | SkyAir, VRV, Heat reclaim ventilator |
| AH Malfunction of dust collector of air cleaner | Defect of dust collecting element Stained insulator part Defect of high voltage power supply unit Defect of indoor unit PCB | RA, SkyAir, VRV, Fan coil |
| AJ Malfunction of capacity setting (Indoor unit PCB) | The capacity setting adaptor was not installed when replacing PCB Defective indoor unit PCB | SkyAir, VRV, Package |
| C1 Failure of transmission (between indoor unit PCB and sub PCB) | Defective connection of the connector between indoor unit PCB | SkyAir, VRV |
| C4 Malfunction of liquid pipe thermistor for heat exchanger | Defective thermistor for liquid pipe Defective indoor unit PCB Defective connector contact | RA, SkyAir, VRV, Package, Heat reclaim ventilator, Chiller, Fan coil |
| C5 Malfunction of gas pipe thermistor for heat exchanger | Defective thermistor for gas pipe Defective indoor unit PCB Defective connector contact | RA, VRV, Package, Heat reclaim ventilator, Chiller |
| C6 Malfunction of fan motor sensor or fan control driver | Defective fan PCB Defective connection of capacity setting adaptor Field setting error | SkyAir, VRV |
| C7 Front panel driving motor fault | Defective front panel driving motor Defective limit switch | RA |
| C9 Malfunction of suction air thermistor | Defective thermistor for suction air Defective indoor unit PCB Defective connector contact | RA, SkyAir, VRV, Package, Heat reclaim ventilator, Fan coil |
| CA Malfunction of discharge air thermistor | Defective thermistor for discharge air Defective indoor unit PCB Defective connector contact | RA, VRV, Package, Heat reclaim ventilator |
| CC Malfunction of humidity sensor system | Defective humidity sensor Defective connector contact | RA, SkyAir, Package |
| CJ Room temperature thermistor in remote controller abnormality | Defective room temperature thermistor in remote controller Defective remote controller PCB External factor (Noise etc.) | RA, SkyAir, VRV, Package, Fan coil |